Otomobil koltuğunda hava yastığı kişiselleştirme

In the past airbags did not only make the headlines as a life rescuer; in individual cases also by malfunctioning that led to injuries or even deaths, e.g. When in an accident children where sitting in a wrong position on the passenger seat. Such tragic incidents can be avoided however, if the airbag activation is synchronized with body size and body weight of the front seat passenger. Nowadays, well thought-out test and calibration plants with more modern sensor systems contribute for maximum security.

In order to get the data, necessary for the appropriate airbag adjustment, different person classification systems are integrated in the front car seats, for example pressure sensitive allocation mats or weight sensors. On the basis of the obtained measured values the required release of the airbags can be adapted to the respective passenger.

Safe front seat passenger classification possibilities

A specialist in this area is the company Stankowitz test equipment, situated in Diepholz (Germany). For more than 30 years, this family company established on the world market develops and manufactures test and optimization systems; not only for the automotive domain, but also for aviation, chemistry and food technology. Nowadays, the test and calibration plants for the current and future integrated classification systems in car seats are used by all automobile seat manufacturers.

Automatic position control with highest precision

Usually the test and calibration systems are directly merged into the assembly line. They can work on the different seat types flexibly in arbitrary sequence. The production pallets are equipped with a fully automatic clamping mechanism for accurate positioning of the seat and are transported to a mechanical station in the test plant. Then, laser distance sensors make sure that the seat reaches its position where seat inclination, leaning and height adjustment are secured.

In addition, the distance sensors measure the distance to the surfaces of the seats in several precisely defined places. The applicable values for that respective seat are lodged in the plant computer with an appropriate legend. Do the measured values of the sensors show that the correct positions are achieved, then the test/calibration starts. Successively the seats undergo various force applications. Also during this process the laser distance sensors are active.

To check the correctness of the calibration and ensure the test results, they are constantly checking the position of the seat. In doing so the sensors must perform considerably: High requirements of the assigned sensor system.

„We have very high requirements towards reproducibility, “describes Reinhard Stankowitz, managing director at Stankowitz test equipment GmbH. „The seat must be very precisely positioned, so that functionality can be tested/ calibrated and afterwards verified. After all, it concerns people’s safety here. “Besides, different reflection characteristics of the seat surfaces may not impair functionality. „We expect reliable measurement results with fabric, with leather or imitation leather upholstering. Bright or dark colors, patterned or plain upholstering, blunt or silk-matted surfaces: all that may have no effect on the quality of the measured results “, complements Stankowitz.

At the same time the sensors must be insensitive to foreign light influences and work with as short a response time as possible.„We found suitable devices, to fulfill these requirements and at the same time with a favorable cost-performance ratio, in the sensor system program of the automation specialist Omron electronics “summarizes Reinhard Stankowitz.

At the test and calibration plants for the front passenger seat classification systems up to four laser distance sensors of the series ZXLD300L are used according to the implementation. The sensors are suitable for distances up to 300 mm, with dissolution of up to 300 µm (averaged worth over 4.096 measure cycles). Distance measurement is based on the triangulation principle.

The laser beam meets on the object and is reflected on a PSD element (Position Sensitive Device). A specifically developed evaluation electronic system computes the distance to the object from the distribution of the reflected light on this receiver element. This system suppresses disturbing reflections, so that the distance finding also provides reliable measurement results with critical objects - like the differently upholstered car seats. The values are converted into distance-proportional output signals and passed on to the super ordinate control system. Foreign light influences up to 3000 lx (a typical office lighting has a density of approximately 500 lx) do not impair the functionality.

Compact, installation-friendly and reliable

But also beyond that the laser distance sensors have plenty to offer. The sensor heads are very compact; their dimensions correspond, with a height of 39 mm, a width of 17 mm and a depth of 33 mm, to those of conventional light barriers. Thus no fear of space problems with installation and the laser distance sensors can also be installed well in the test and calibration plants. The same is valid for the small amplifiers.

They have a width of only 31 mm, a height of 30 mm and are 64 mm long. Nevertheless they offer a multiplicity of intelligent and user-friendly functions, e.g. scaling, swiveling range, sensitivity selection, different parameter possibilities, Teach in etc. The test specialists from Diepholz are content with their sensor choice. „Apart from the high reliability also the longevity of the laser distance sensors convinced us “says Stankowitz. After all, unexpected sensor losses will momentarily bring the complete test system to a halt. „Therefore, we install, as one of the first users at the moment, a completely new sensor head from the house of Omron at our test systems“, Stankowitz continues to report. Owing to the large measuring center distance of 2,000 mm the laser displacement sensor can be easily installed firmly within the head framework for the testing equipment. Thus one saves the mechanics for the procedure unit, wins space and accelerates in addition the test and/or calibration procedure.

Furthermore, also another optical sensor could prove its reliability in the test and calibration plants in the meantime. A vision sensor examines springs and bolts on the bottom surface of the car seats on presence and positioning. At the same time it controls, whether the test plugs are put on the seat, because only then, the test system can take up its work. The small image processing system with integrated lighting is simply to program and can be combined with different camera units. When two cameras are attached, the pictures can alternatively be processed successively or combined. Optical sensor systems in different configurations contribute thereby substantially to clearly improve motor vehicle safety for the passengers.